The stout iguana, Cyclura pinguis (also known as the Anegada iguana), survives only in the British Virgin Islands and the total population is believed to be about 250 individuals. The sole remaining natural population, on Anegada, is declining in both numbers and area inhabited. Several extra-limital populations have been established, and here we report on body size and timing of egg-laying in the Guana Island population, which is thriving. Egg laying occurs in June and July, and hatchlings emerge in September and October. For hatchlings, mean snout-vent length was 108 mm, mean undamaged tail length was 197 mm, and mean mass was 60 g. Growth of hatchlings is rapid. Overall, the relationship between log mass and log body length is statistically significant. Comparisons to data published for Anegada animals show that iguanas of similar length weigh more on Guana, suggesting possible food limitation in the Anegada population. Until progress is made towards establishing a national park on Anegada, reintroduced populations, such as the one on Guana, constitute a critically important precautionary measure for Cyclura pinguis. Moreover, we strongly recommend enhancing the Guana gene pool.